In general, you should pay for content that you're going to use commercially

Sure, but merely linking to a page isn't reusing the content. If said content was being embedded, rehashed or otherwise shown then a compensation would be fair. But merely linking to a page should absolutely be free. That's a massively important cornerstone of the internet that shouldn't be compromised on.

Linking directs traffic which can be monetized by the website itself, it shouldn't require additional fees on top.